Well, check where it says "Default Settings". You can define your own naming scheme for Save for Web there. Though, to be fair, if you plan to actually use your files on the web, you really should save them with hyphens or underscores.

The JPEG preview files have modified filenames. If you choose to generate the ancillary JPEG preview file when extracting, you will notice that filenames with spaces are modified to have dashes instead. For example, the JPEG of the file "My Example.ai" will be "My-Example.ai.jpeg" instead of "My Example.ai.jpg". This is because Illustrator forces filenames without spaces.

I use Illustrator and constantly need to change hundreds of file names because Illustrator doesn't allow an option to remove dashes.

Really? Hundreds? Constantly?

I don't get it. If you want spaces in your file names, why are you using Save for Web? Or, why are you saving files for web use with spaces in the file name? The induced hyphens are by design. Spaces are allowed when saving any other way.

There may or may not be, but one would need a more thorough understanding of your workflow in order to find one. I still don't understand why you would want spaces in the names of web-format files; to the extent that you'll take extra steps to get them back.

How about this... I'm saving tons of wireframes out of Illustrator as PNGs. They're not meant for the web and it's fine that there are spaces in the names.

There were already many dozens of these in the folder and they had a very specific file naming convention in place that allowed spaces. Now, along comes the newest version of Illustrator, with the HTML output settings dialog removed. And suddenly my naming convention is broken and the only way to fix it is to rename all the existing files.

But see... this is about control. If I want to make files with spaces in the name I should be able to. Every other program on my computer... including Photoshop, InDesign, and other Adobe products, all allow this.

You guys removed the HTML output settings dialog and didn't replace the functionality in another place. And now I'm in a jam.

If you use the "Save for web" function, then one might safely assume you want to save a file for the web (because it does a bunch of other things on top of the hyphen, such as converting your image to RGB and attaching an sRGB color profile). If you don't want to save a file for the web, then use "Export".